The present invention relates to a normally feeding wiring harness excess length absorbing device which absorbs an excess length of a wiring harness by curving the wiring harness into a substantially semi-annular shape and expanding and contracting a curved portion resulting from the curving of the wiring harness.
FIGS. 20 to 21 show one form of a conventional wiring harness excess length absorbing device (JP-A-10-181473 (FIGS. 6 to 8)).
This wiring harness excess length absorbing device 71 is such that a wiring harness 73 is curved into a loop within a case 72 in such a manner as to exit from one opening 74 and the other opening 75 of openings formed in the case 72 and that a loop portion 73a of the wiring harness 73 is biased by a leaf spring 76 in a direction in which it expands diametrically.
As shown in FIGS. 22A to 22B, this wiring harness excess length absorbing device 71 is mounted on a front side door 77 of an automobile such that when the door 77 is closed as shown in FIG. 22A, the wiring harness 73 expands diametrically within the case as shown in FIG. 20, whereas when the door 77 is opened as shown in FIG. 22B, the wiring harness 71 is pulled out of the case 72 and the loop portion 73a contracts diametrically as shown in FIG. 21. The wiring harness 73 connects to a power supply side at one end and an auxiliary device within the door at the other end thereof. In the figures mentioned above, reference numeral 78 denotes a locking clip for fixing the wiring harness 73 to a vehicle body 79.
This wiring harness excess length absorbing device 71 is designed to be mounted on not only the door 77 but also the vehicle body 79. In addition, in place of the leaf spring 76, a coil spring may be mounted on the wiring harness 73 within the case so as to pull the wiring harness 73 into the case by means of biasing force of the coil spring (refer to JP-A-10-181476 (FIG. 5)).
As a wiring harness excess length absorbing device other than those described above, for example, JP-A-2001-354085 (FIG. 4) proposes a wiring harness excess length absorbing device for an automotive sliding door (not shown). In this wiring harness excess length absorbing device, a wiring harness is accommodated in a case in such a manner as to be bent into a substantially semi-circular shape by virtue of biasing by a leaf spring, and one end of the wiring harness is made to exit towards a sliding door side auxiliary device from a front opening in the case, whereas the other end of the wiring harness is made to exit towards a vehicle body from a lower opening in the case in such a manner as to swing freely.
When the sliding door is closed, the wiring harness is pulled out to the rear while supported at a vehicle body side fixing portion, whereas as the sliding door is being opened, an excess length of the wiring harness is absorbed by the leaf spring, and when the sliding door is opened, the wiring harness is pulled out to the front while supported at the fixing portion.
In the conventional wiring harness excess length absorbing device 71 shown in FIG. 20, however, since the wiring harness 73 intersects itself within the case, there is caused a problem that portions of the wiring harness 73 which intersect each other tend to rub against each other, whereby the wearing down of the relevant portion is facilitated. In addition, since the wiring harness 73 is expanded and contracted in the loop, when attempting to set its extending and contracting stroke large, the wiring harness 73 is contracted to a small diameter and a large bending load is applied to the wiring harness 73, and this works to reduce durability and enlarge the case, causing a problem that the extending and contracting stroke (excess length absorption length) is difficult to be set. In addition, since the wiring harness 73 is pulled into the case direct by the spring member 76, the large spring member 76 is necessary, and this works to enlarge the mechanism and imposes a limitation on the configuration of the spring member 76. Additionally, since the metallic spring member 76 is brought into direct contact with the wiring harness 76, there is caused a problem that the insulation sheathing of the wiring harness 73 becomes easy to wear. In addition, the spring member 76 causes other problems that the number of components is increased, the mechanism is enlarged, an additional man-hour is necessary to separate the resin case 72 from the metallic spring member 76 when disassembling the mechanism for recycling, and when a coil spring is used as the spring member, the wiring harness 73 has to be passed through the coil spring, deteriorating the assembling properties of the mechanism.